JPH1075181A5 - - Google Patents

Claims (3)

1. A method of decoding an encoded data stream having codeword-coefficient pairs of maximal length "Q", comprising the steps of:
storing a first input data set having a number of bits comprising first pairs of coefficients and Huffman code words in a data register having a data capacity at least twice Q;
receiving a next sequential input data set comprising a second coefficient-Huffman codeword pair of the stream in a shift register;
right shifting said next sequential input data set by the number of bits in said first data set;
, performing a logical OR of said first input data set and said next sequential input data set and placing the result in a data register;
extracting the N most significant bits of the data register as a decoded coefficient value and the M next most significant bits of the data register as a codeword;
A method comprising: 1. An input data stream decoder for variable length coded bit string codeword-coefficient pairs, the input data stream further comprising byte boundary codes and header/marker codes;
a decoding means for sequentially receiving and decoding the codeword-coefficient pairs,
input shifting means for receiving at least two input data sets;
means for performing a logical OR operation on the current input data set and the next input data set that follows it;
means for storing and shifting a bit string resulting from the logical OR operation of the current input data set and the subsequent next input data set;
means for separating the codeword-coefficient pairs into codewords and coefficients;
means for examining said codeword and extracting therefrom a decoded address;
means for shifting said storing and shifting means by the sum of the length of the current codeword and the length of the coded coefficient;
decoding means having
An input data stream decoder having: 1. A method for decoding a JPEG/MPEG compressed data bit stream having words of maximum bit length "Q", comprising:
receiving successive input data words to be decoded in an input register having a bit capacity of at least twice Q;
appending each successive input data word to the input data word preceding it in said input register;
right-shifting each new data word in said register by a number of valid data bits, said number of valid data bits being the number of bits in the previous input word;
performing a logical OR operation on two consecutive input data words;
storing the result of said OR operation in an operational data register;
shifting the operational data register left based on the number of bits in the preceding codeword-coefficient pair, and extracting the N most significant bits of the operational data register as the value of the decoded coefficient and the M most significant bits as the Huffman codeword;
A method having the following.